In parallel, in common workshop use, particularly in the field of plumbing, i.e. those companies and/or units specialized in the production of tubes, flanged fittings, manifolds with joints etc. has stimulated the development of another category of positioners which is located, by its type of use and conformation, between the two main categories introduced above.
Said solution provides two lower support rollers and one upper “antagonist” roller which by tightening upon the work-piece ensures gripping thereof. The gripping is obtained by way of a fixed support column of the antagonist roller and by an adjusting screw for approaching the roller to the work-piece.
The solution is effective but the presence of the counter-roller “in irremovable position” makes the loading and unloading operations of the work-piece uncomfortable, in addition to imposing relatively narrow limits on the diameters of the loadable pieces.